The invention relates to a touch sensitive screen with haptic feedback.
Touch sensitive screens, which are also known by the designation of touchscreen, consist of a combination of a display device having a transparent, touch sensitive operating device arranged thereon. Upon being touched by a finger or a stylus, the touch sensitive operating device, which is also known under the designation of touchpad, generates an electrical signal that can be converted into a command, for example for displacing a cursor on the display device, or for selecting a menu option. Such touchscreens and touchpanels are sufficiently known.
Since, by contrast with conventional keys, touch sensitive screens have no pressure point, it is frequently unclear to the operator whether the operation he has undertaken has been detected. In order to give the user feedback in this respect, touch sensitive screens with haptic feedback are already known. Thus, DE 101 54 643 A1 describes an operating device for a screen controlled process that has a touch sensitive input field. The operating device has an electric motor, which is connected to an eccentric, for feedback. Alternatively, the input field can also be set to vibrate by means of ultrasound. The display area and the input area form a structural unit in the configuration as touchscreen.
US 2003/0184574 A1 discloses a touch sensitive screen in the case of which a touch sensitive arrangement is arranged on a plate at a distance from a display device. One or more actuators are connected to the plate and serve to produce haptic feedback when the plate is touched. The haptic feedback takes the form of vibrations or pulses.
Thus, in the case of such a touch sensitive screen a light transmitting, that is to say transparent, touchpanel is placed in front of the display device such that the graphic elements or alphanumeric characters displayed on the image side of the display device lie directly behind the control surfaces of the touch sensitive arrangement and are visible through them. There is the need in this case for a slight distance between the touch sensitive arrangement and the image side of the display device in order to avoid negative optical effects, it being possible, for example, for there to be an offset of the optical axis (parallax error) or image blurring. Dust or dirt that impairs the optical appearance can now penetrate into the interspace between the image side of the display device and the touch sensitive arrangement. The penetration of moisture with resultant misting over of the display device can also occur, particularly during use in motor vehicles.